Bearing seal with flexible lip

ABSTRACT

A seal is disclosed for use on the tapered section of a roll neck in a rolling mill. The seal comprises a flexible circular seal body having a central axis and at least one radially outwardly extending flange joined by a hinge to an angularly extending lip. The hinge has a reduced thickness as compared to the thicknesses of the flange and the lip, and the lip has converging first and second sides leading to an enlarged rim. The rim has first and second peripheral faces that converge to an outer edge contained in a reference plane parallel to the central axis of the seal body.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Provisional Patent ApplicationSer. No. 60/600,871 filed on Aug. 12, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to flexible seals for bearingapplications, and is concerned in particular with a flexible lip seal ofthe type employed in rolling mill oil film bearings.

2. Description of the Prior Art

One example of a prior art seal design is disclosed in U.S. Pat. No.2,868,574, wherein a seal is surrounded by a stationary circular sealend plate having a radially inwardly extending rigid flange separatingoppositely arranged shoulders. The flexible seal has radially outwardlyextending flexible flanges which are in sliding contact with inclinedsurfaces on the shoulders of the seal end plate. The flange/shouldersurface interface on the inboard side serves to retain bearing lubricantin the bearing, and the flange/shoulder surface interface on theoutboard side serves to exclude contaminants such as cooling water, millscale, etc. from penetrating into the bearing.

This design exhibits problems such as leakage of the bearing lubricant,contaminant entering the bearing chamber and excessive wear of the sealcomponents. These problems are due in large part to the seal flangeswhich are thick and heavy throughout their length. Therefore, theflanges are not as flexible as they should be and have a tendency tobecome distorted and fail to provide an effective seal.

In the seal design disclosed in U.S. Pat. No. 4,165,881, these problemwere addressed by providing the seal flanges with peripheral relativelythin flexible lips. This design resulted in improved sealingperformance, but leakage problems persisted when the seal was notproperly aligned with respect to the seal end plate.

A need has continued to exist, therefore, for a seal that can operateeffectively under all operating conditions, including those in which theseals are improperly aligned with respect to the seal end plates.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved seal has acircular seal body with a central axis and at least one radiallyoutwardly extending flange joined by a hinge to an angularly extendingsealing lip. The hinge has a reduced thickness as compared to thethicknesses of the flange and lip. The lip has converging sides leadingto an enlarged rim, and the rim has angled peripheral faces thatconverge to an outer edge.

In its operating environment, the seal is mounted on the tapered sectionof a roll neck, with the outer edge of the sealing lip in slidingcontact with an adjacent shoulder of a seal end plate. Flexure of thesealing lip at the hinge serves in concert with the increased mass andstiffness of the enlarged rim and the angular relationship of theperipheral faces to maintain line contact between the outer edge of thesealing lip and the shoulder of the seal end plate.

These and other features and advantages of the present invention willnow be described in further detail with reference to the accompanyingdrawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view taken through the seal assembly of arolling mill oil film bearing, and showing a flexible neck seal inaccordance with the present invention;

FIG. 2 is an enlarged cross-sectional view of the inboard flange on theneck seal depicted in FIG. 1.

DETAILED DESCRIPTION

Referring now to the drawings, and with initial reference to FIG. 1,there is shown at 2 a roll having an end face 4 and a roll neck with atapered intermediate section 6 leading to a more gradually tapered endsection 8. A sleeve 10 is mounted on the tapered end section 8 and isfixed relative to the roll neck by conventional means (not shown) forrotation therewith. The sleeve 10 has an outer bearing surface 12 whichis journalled for rotation within an interior bearing surface 14 of afixed bushing 16 which is carried in a roll chock 18.

The sleeve 10 rotates with the roll while the roll chock 18 and thefixed bushing 16 are stationary. Oil in flooding quantity is fedcontinuously between the bearing surfaces 12 and 14. A circularextension 20 of the roll chock provides at its bottom portion a sump 22in which the oil emerging from the bearing is continuously collected.The oil is drawn away from the sump to be recycled back to the bearingsurfaces.

Where the roll 2 is operating under “wet” conditions, coolant fluid isconstantly flooding over the roll 2 and down over the end face 4. Inspite of the centrifugal forces which tend to throw the coolant off ofthe roll, some of the coolant tends to work its way along the roll neckin the direction of the bearing. The objective of the seal assemblygenerally indicated at 26 and the flexible neck seal 28 which forms apart of the bearing assembly, is to prevent any of the coolant fluidfrom reaching and contaminating the bearing oil and, vice versa,preventing loss of oil from the bearing.

The flexible neck seal 28 includes a flexible circular seal body 30having inner surfaces 32 a, 32 b adapted to be mounted in sealingengagement on the tapered section 6 of the roll neck. The neck seal 28is molded of a suitable resilient rubber-like material. Optionally, theseal body 30 is internally reinforced by an embedded combination of acoiled spring 34 and a steel cable 36.

The seal body 30 has an exterior cylindrical surface 38 parallel to itscentral axis “A”. Inboard and outboard circular flexible flanges 40, 42extend radially from the seal body 30 at opposite ends of surface 38.

The outboard flange 42 is provided with a conventional flexible lip 44joined to the flange by a hinge 46 of reduced thickness. Referringadditionally to FIG. 2, the inboard flange 40 also has a lip 48 joinedto it by a hinge 50 of reduced thickness.

In accordance with the present invention, lip 48 has converging firstand second sides 48 a, 48 b leading to an enlarged rim 52. The rim 52has first and second peripheral faces 54 a, 54 b that converge to anouter edge 56. When the seal is in a relaxed unstressed state (notconfined or otherwise distorted), the outer edge 56 is contained in areference plane “P” parallel to the central axis “A”.

When the seal is in its operating environment as depicted in FIG. 1,both lips 44 and 48 are in respective sliding contact with adjacentshoulders 58 of a seal end plate 60. The conventional lip 44 is onlyrelatively lightly loaded against its respective shoulder 58, and theresulting area contact at the lip/shoulder interface is not conducive tomaintaining a hydrodynamic condition. Seal misalignment furtherexacerbates this condition, causing accelerated wear and leakage.

In contrast, the outer edge 56 of lip 48 is in line contact with itsrespective shoulder 58. As the neck seal rotates with the roll neck, theextra mass of the enlarged rim 52 serves to centrifugally urge the outeredge 56 into sealing contact with the surrounding shoulder surface. Theangled relationship of the peripheral faces 54 a, 54 b coupled with theincreased stiffness of the enlarged rim 52 ensures hydrodynamic actionon both sides of the outer edge 56 as the lip 48 flexes about the hinge50 to compensate for seal misalignment.

In order to further enhance the aforesaid advantages, and as can best beseen in FIG. 2, the first and second sides 48 a, 48 b are arranged todefine an included angle {acute over (α)}₁ of between about 4° to 10°,with the preferred angle being about 7°.

In the relaxed unstressed state, the first side 48 a of the lip isarranged at an angle of {acute over (α)}₂ with respect to referenceplane P of between about 46° to 54°, with an angle of about 50° beingoptimal. The second side 48 b is arranged at an angle {acute over (α)}₃with respect to the reference plane P of between about 39° to 47°, withan angle of 43° being optimal. The included angle {acute over (α)}₄defined by peripheral faces 54 a, 54 b is preferably between about 90°to 106°, with 98° being optimal.

Advantageously, the first side 48 a and the first peripheral face 54 adefine an included angle {acute over (α)}₅ of between about 66.5° to77.5°, with 72° being optimal. The second side 48 b and the secondperipheral face 54 b define an included angle {acute over (α)}₆ ofbetween about 157.5° to 168.5°, with 163° being optimal.

The first side 48 a is advantageously provided with a protuberance 62spaced inwardly from the juncture of the first side 48 a with the firstperipheral face 54 a. Protuberance 62 is preferably formed as asemi-circular rib.

The aforesaid angular relationships contribute to enhanced sealingperformance of the hinged lip 48 as incorporated in a range of sealsizes. Line contact of the outer edge 56 with an adjacent fixed surfaceis maintained regardless of the degree of seal misalignment, thusoptimizing retention of lubricant and exclusion of contaminants.

Although not shown, it will be understood that instead of being providedwith a conventional lip 44, the outboard flange could also be providedwith a lip 48 in accordance with the present invention.

1-15. (canceled)
 16. A seal for use on the tapered section of a rollneck in a rolling mill, said seal comprising: a flexible circular sealbody having a central axis and at least one radially outwardly extendingflange joined by a hinge to an angularly extending lip, said hingehaving a reduced thickness as compared to the thicknesses of said flangeand said lip, said lip having converging first and second sides leadingto an enlarged rim, said rim having first and second peripheral facesthat converge to an outer edge contained in a reference plane parallelto said central axis, said first side and said first peripheral facedefining an acute included angle ({acute over (α)}₅), and said secondside and said second peripheral face defining an obtuse included angle({acute over (α)}₆).
 17. The seal as claimed in claim 16 wherein saidfirst and second sides define an included angle ({acute over (α)}₁), ofbetween about 4° to 10°.
 18. The seal as claimed in claim 17 whereinsaid included angle ({acute over (α)}₁) is about 7°.
 19. The seal asclaimed in claim 16 wherein when said flange and said lip are in anunstressed condition, the first side of said lip is arranged at an angle({acute over (α)}₂) of between about 46° to 54° with respect to saidreference plane.
 20. The seal as claimed in claim 19 wherein said angle({acute over (α)}₂) is about 50°.
 21. The seal of claim 16 wherein whensaid flange and said lip are in an unstressed condition, the second sideof said lip is arranged at an angle ({acute over (α)}₃) of between about39° to 47° with respect to said reference plane.
 22. The seal as claimedin claim 21 wherein said angle ({acute over (α)}₃) is about 43°.
 23. Theseal of claim 16 wherein said first and second peripheral faces definean included angle ({acute over (α)}₄) of between about 90° to 106°. 24.The seal as claimed in claim 23 wherein said angle ({acute over (α)}₄)is about 98°.
 25. The seal as claimed in claim 16 wherein the includedangle ({acute over (α)}₅) defined by said first side and said firstperipheral face is between about 66.5° to 77.5°.
 26. The seal as claimedin claim 25 wherein said included angle ({acute over (α)}₅) is about72°.
 27. The seal as claimed in claim 16 wherein the included angle({acute over (α)}₆) defined by said second side and said secondperipheral face is between about 157.5° to 168.5°.
 28. The seal asclaimed in claim 27 wherein said included angle ({acute over (α)}₆) isabout 163°.
 29. The seal as claimed in claim 16 further comprising aprotuberance on the first side of said lip location spaced inwardly fromthe juncture of said first side and said peripheral first face.
 30. Theseal as claimed in claim 29 wherein said protuberance comprises a ribhaving a semi-circular cross section.